Patent Literature 1 discloses a centrifugal multi-blade blower fan. Such a centrifugal multi-blade blower fan is generally referred to as a centrifugal fan and includes a boss plate of a circular shape viewed from the front in which a cylindrical support section is provided at a center and a plurality of blades are provided at regular intervals at an outer circumference of the boss plate in the circumferential direction as shown in FIGS. 1 and 2 of Patent Literature 1. The blades have shapes extending in parallel with each other in a direction of a central axis of rotation of the boss plate. Also, a leading edge (an inner circumferential edge) and a trailing edge (an outer circumferential edge) of each of the blades are both in parallel with the central axis of rotation. In such a centrifugal multi-blade blower fan, a rotation shaft of a motor is mounted on the cylindrical support section and is rotatably driven so that external air is suctioned in one direction in the direction of the central axis of rotation and is discharged in a radial direction of the boss plate.